Stud shallow hole ore breaking safe recovery mining method under stope collapse condition

Abstract

The invention provides a safe recycling and mining method for a stud under the condition of collapse of a stope, and relates to the technical field of underground mining. In order to solve the problem that the stope is fully filled with ore-rock mixtures due to the fact that filling is not carried out in time in open stope method stoping, according to the arrangement mode of an original chamber stope, a footwall transportation roadway and a mining raise are tunneled in a footwall of an ore body, rock drilling transverse drifts penetrating upper and lower footwall are arranged in the mining raise at the interval of 5-6 m, and triangular pillars are reserved at the bottom; a bottom-to-top layered shallow hole retreating type blasting process is adopted, part of ore is temporarily reserved to serve as a working platform and an anti-collapse barrier, personnel always work in a rock drilling transverse drift, and safe recycling of the stud can be achieved without filling; the method is suitable for small and medium-sized mines, the mining-cutting ratio is remarkably reduced, ore dilution is effectively controlled, the resource recovery rate is remarkably increased, and economical, efficient and safe recovery of the collapsed stope stud is achieved.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology, specifically to a safe mining method for shallow-hole ore recovery under conditions of mine collapse. Background Technology

[0002] The stope retention method was once a widely used mining method in my country's underground mines, especially in gold, non-ferrous metal, and chemical mines. This method is particularly suitable for mining thin and very thin veins due to its relatively simple process, ease of operation, and convenient management. The standard mining sequence is to first recover the stope, then the pillars. After the stope is recovered, the stability of the goaf mainly relies on the reserved pillars and the surrounding rock for support. However, the traditional stope retention method has a significant inherent drawback: the pillars (such as inter-pillars and roof pillars) reserved to ensure stope stability result in substantial ore resource losses. Practice shows that the total ore recovery rate of this method is typically only between 40% and 60%. This stope-pillar abandonment model leads to a serious waste of mineral resources and has become a key bottleneck restricting the improvement of mine economic efficiency and the intensive utilization of resources.

[0003] To improve resource recovery rates, the industry currently widely adopts post-mining technology. This involves filling the goaf with tailings, waste rock, or cementing materials after the stope has been mined, forming artificial supports to recover the reserved pillars under relatively safe conditions. However, the successful application of post-mining technology strongly relies on a fundamental premise: the goaf must maintain a relatively stable morphology to facilitate effective filling operations. For some mines where backfilling was not carried out in a timely manner due to historical mining or intense ground pressure activity, the goaf may have collapsed, filled with loose and unstable ore-rock mixtures. Under such adverse geological conditions of "collapsed stope," not only can conventional backfilling operations not be implemented, but the collapsed material also poses significant safety hazards and technical challenges to subsequent pillar recovery. Any recovery operation is highly susceptible to disturbing the loose material on both sides, causing it to surge into the working space, not only preventing recovery work but also resulting in severe ore dilution losses and safety accidents. The invention patent with publication number CN114961731A provides a method for recovering pillars in the goaf of an inclined thin ore body by subsequent filling with manufactured sand. Utilizing existing transport roadways and ventilation shafts, a downward inclined ramp is designed along the upper and middle sections of the vein to reach the stope. Manufactured sand cemented filling technology is used to form an artificial pillar with a 2m thick cemented filling body inside the stope, ensuring the safety of stope recovery. Although this patent can improve the safety of recovery under certain conditions, it has clear limitations: First, the essence of this method is "filling before recovery," and its effectiveness depends entirely on the successful filling of the goaf. Therefore, it cannot solve the specific technical problem of "the stope has collapsed and cannot be filled," which is the focus of this invention. Second, the process of constructing the artificial filling pillar itself increases additional costs and operating time, affecting the timeliness of recovery.

[0004] The invention patent with publication number CN120331778A provides a novel shallow-hole mining method with pillar recovery. The ore body is mined sequentially from top to bottom. After the mining of the upper section of the ore body is completed, the next section's unmined stope and pillars are mined. The pillars being mined are connected to the external ventilation and filling shafts located in the footwall of the ore body via pillar connecting tunnels. The lower end of the external ventilation and filling shafts is connected to the top of the pillar ore extraction roadway in that section, and the top end is connected to the upper section pillar ore extraction roadway. The right end of the upper section pillar ore extraction roadway is connected to the upper section transport roadway. However, the mining method is still based on the premise that the pillars and stopes were not mined in the early stages, and then the pillar stopes are mined first. During the mining of the pillar stopes, pillar connecting tunnels are added, and the bottom is mined by layered blasting. After the upper ore body falls back to the level of the pillar connecting tunnels, mining continues upwards. After the pillar recovery work is completed, the remaining pillars are returned to the mining area. However, this method has drawbacks such as complex processes, low initial ore recovery volume, and low efficiency. Current technology lacks a safe pillar recovery method that can effectively address extremely complex conditions such as stope collapse, ore-rock mixture intrusion, and the inability to implement conventional backfilling.

[0005] In view of this, it is necessary to study a safe and economical mining method for shallow hole mining of pillars under the condition of mine collapse, which can directly achieve safe, economical and efficient recovery of pillar resources in such high-risk environments without relying on pre-filling, so as to revitalize residual mineral resources that cannot be utilized by traditional technologies. Summary of the Invention

[0006] In view of the technical problems existing in the background art, the present invention provides a safe recovery mining method for shallow hole ore extraction with pillars under the condition of stope collapse. In response to the unique ore conditions of unfilled collapsed stopes and mixed ore-rock masses on both sides of the pillars, the stopes are laid out perpendicular to the ore body strike. First, a haulage roadway is excavated 5-6 meters from the ore body along the footwall. A mining raise is then constructed within the footwall haulage roadway, with drilling veins extending to the upper ore body boundary. Drilling veins are placed every 5-6 meters in height, and a triangular pillar is reserved at the bottom closest to the upper body to facilitate ore flow to the bottom for later loading. Given that the pillar stopes are surrounded by mixed ore-rock masses, the first layer of ore body is recovered during pillar mining. Subsequent mining is carried out within the drilling veins of each layer, ensuring personnel safety. Shallow-hole blasting is used, mining proceeding sequentially from bottom to top. Personnel are always within the drilling veins during the mining of each layer, ensuring their safety. Shallow-hole mining minimizes the impact of blasting vibrations on the side stops, preventing large-scale collapses in the side stops that could pose safety hazards for pillar recovery. This ensures safe, economical, and efficient pillar recovery.

[0007] This invention provides a safe mining method for recovering ore from shallow-hole pillar mining under conditions of stope collapse. Specifically, it addresses orebody conditions where the stope has collapsed and is unfilled, with the pillars flanked by a mixture of collapsed ore and rock. The method utilizes the existing stope layout, recovering only the pillar ore without stope backfilling. The specific steps include: S1, Preparatory work layout: A footwall transport roadway parallel to the strike of the ore body is excavated in the footwall surrounding rock; and a mining riser is excavated at the corresponding pillar position in the footwall transport roadway; the mining riser is connected to the upper and middle sections to form a safety passage; S2, Formation of Layered Operation Channel: In the mining riser, rock drilling veins are excavated in layers along the vertical direction. The rock drilling veins extend from the lower boundary of the ore body to the upper boundary of the ore body. In the bottommost rock drilling vein, a guide pillar is reserved on the side near the upper side of the ore body. S3, Layered mining operation: Personnel enter the mining shaft from the lower transport roadway, and then enter the drilling veins of each layer. Under the protection of the drilling veins, retreat mining is carried out, using shallow hole ore cutting method, and the pillar ore body is mined from bottom to top. S4, Ore Management: After all the layered mining is completed, the ore is extracted in a centralized manner through the lower transport roadway. The reserved ore pillars are used to guide the ore to the bottom of the stope for easy loading and unloading operations.

[0008] As a further improvement of the present invention, in step S3, the specific recovery process is as follows: S31, starting from the bottom of the rock-drilled vein layer, personnel enter the rock-drilled vein and use the rock-drilled vein as the working space to construct blast holes, and use shallow hole ore-dropping method for retreat blasting. S32, after blasting, some ore is released, and the remaining ore is temporarily left as a working platform for the next layer of mining and a barrier to prevent the mixed ore and rock from entering the collapsed ore-rock mixture. S33. Repeat steps S31 to S32 layer by layer from bottom to top until all the intercolumns are mined.

[0009] As a further improvement of the present invention, in order to avoid the loose ore and rock from the original stope from mixing into the inter-pillar stope during inter-pillar mining, measures are taken to reduce the stratification height of the inter-pillar stope; the stratification height of the rock drilling vein is 5-6 meters, and the roadway cross-section is 3 meters × 3 meters.

[0010] As a further improvement of the present invention, in step S2, the guide pillar is a triangular pillar; the shape and size of the triangular pillar are adapted to the natural ore flow trajectory to ensure that all the upper layer ore flows to the bottom of the mining area.

[0011] As a further improvement of the present invention, in step S31, the blast holes are arranged obliquely upwards, with a blast hole depth of 1.8~2.2m and a hole spacing of 0.6~0.8m. Micro-delay blasting technology is adopted to control the blasting vibration intensity and avoid causing instability of the rock-rock mixture that collapses on both sides.

[0012] As a further improvement of the present invention, in step S32, the amount of temporarily retained ore is 30% to 40% of the total amount of blasted ore in the layer, and the height of the temporarily retained ore pile is level with the bottom elevation of the next layer of rock drilling vein.

[0013] As a further improvement of the present invention, forced ventilation is adopted during the mining process. Fresh air flows sequentially through the lower transport roadway, mining raise, rock drilling vein, and working face; polluted air enters the mining raise and upper and middle section drilling vein roadway through the rock drilling vein and is discharged to the surface, forming a ventilation loop.

[0014] As a further improvement of the present invention, the width of the pillar is 6 to 10 meters, the length of the stope is consistent with the thickness of the ore body, and the mining height is 25 to 60 meters.

[0015] As a further improvement of the present invention, the distance between the mining riser and the lower boundary of the ore body is 5 to 6 meters, and the cross-sectional dimensions of the lower transport roadway are adapted to the passage requirements of the loader.

[0016] As a further improvement of the present invention, the method is applicable to ore bodies where the mine collapses and the interior is filled with a mixture of ore and rock after the mine was mined using the open-field method and not backfilled in time.

[0017] Beneficial effects: This invention still follows the original layout of mining stops, requiring only a structural arrangement of footwall haulage roadways, mining raises, layered drilling veins connecting the footwall and footwall, and bottom triangular pillars. The core mining process is bottom-up, layered, shallow-hole retreat blasting. By temporarily retaining some ore as a working platform and preventing collapse, safe recovery of pillars can be achieved without backfilling. It possesses the following technical advantages: 1. Safety Assurance Technology Effectiveness: A closed working space is constructed through a mining raise and layered drilling, ensuring personnel always operate within the drilling vein, avoiding direct exposure to the collapsing ore-rock mixture environment, eliminating the risk of collapse, and guaranteeing personnel safety. Shallow-hole ore extraction combined with retreat blasting results in low blasting vibration intensity, preventing instability of the loose ore-rock mixture on both sides, reducing the risk of secondary collapse, and ensuring controllable blasting safety. A complete ventilation circuit is constructed from the lower transport roadway to the mining raise to the drilling vein, ensuring a fresh air supply to the working face and timely removal of contaminated air and harmful blasting gases, guaranteeing ventilation safety.

[0018] 2. Optimized Resource Recovery: Addressing the challenge of inaccessible backfilling in collapsed stopes, this method eliminates the need to abandon pillar resources. Precision mining significantly improves resource recovery rates. The bottom triangular pillars guide ore flow, temporarily retaining ore to form a barrier against contamination, effectively preventing the intrusion of collapsed ore-rock mixtures and significantly reducing ore dilution. Furthermore, by lowering the stratification height, it prevents the collapse of ore-rock mixtures from the original stope into the pillar stope during mining, thus avoiding increased dilution losses. The triangular pillar areas can be flexibly reserved or filled to maximize the recovery of usable ore and avoid permanent resource loss due to collapse, as is common in traditional methods.

[0019] 3. Cost Control Benefits: By utilizing existing vein-side roadways, the preparatory work only requires the addition of a lower haulage roadway, mining raise, and drilling through the vein, significantly reducing the amount of tunneling work. This aligns with the low-cost requirements of small and medium-sized mines and lowers the mining-to-cut ratio. There is no need for backfilling operations in collapsed or pillared stopes, avoiding additional costs associated with backfill materials, equipment, and construction. Ore is guided and concentrated to the bottom of the stope via triangular pillars, and then conveniently extracted through vein-side and vein-side roadways, reducing secondary transfer costs and simplifying the extraction process.

[0020] 4. Adaptability and Operational Efficiency: Specifically designed for the unique scenario of unfilled collapsed stopes and mixed ore-rock masses, it solves the problem of pillar recovery that traditional mining methods cannot address, demonstrating strong adaptability to various scenarios. The mining process involves layered vein excavation → shallow-hole blasting → localized ore extraction → layer-by-layer upward movement. The steps are clear, requiring no complex equipment, making it easy to implement in small and medium-sized mines. The process is simple and easy to operate. It is suitable for thin ore bodies, extremely thin veins, and medium-thick steeply dipping ore bodies, and can accommodate pillar widths of 6-10m, offering flexible application scenarios.

[0021] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0022] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0023] Figure 1 This is a front view of the mining layout structure constructed by the method for safe recovery of pillars under mining conditions provided in this embodiment of the invention; Figure 2 This is a side view of the mining layout structure constructed by the method for safe recovery of pillars under mining conditions provided in this embodiment of the invention. Figure 3 This is a top view of the mining layout structure constructed by the method for safe recovery of pillars under mining conditions provided in this embodiment of the invention.

[0024] Explanation of reference numerals in the attached figures: 1. Lower transport roadway; 2. Mining riser; 3. Drilling through vein; 4. Along-vein roadway; 5. Through-vein roadway; 6. Roof pillar; 7. Blasting hole; 8. Collapsed ore; 9. Triangular pillar; 10. Upper and middle section along-vein roadway; 11. Collapsed ore-rock mixture in the stope. Detailed Implementation

[0025] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0031] In the description of the embodiments of the present invention, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0032] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0033] Addressing the unique technical challenge of collapsed stopes filled with ore-rock mixtures that cannot be filled, this invention proposes a safe and efficient shallow-hole pillar mining method for recovering pillars under collapsed stope conditions. This comprehensive recovery method utilizes external risers and drilling through the vein as rigid safety barriers, and shallow-hole pillar mining, triangular pillars, and dynamic ore retention as low-disturbance dilution control. It aims to solve the problem of pillar recovery under collapsed stope conditions. It is particularly suitable for the low-cost, safe, and efficient recovery of pillar resources in small and medium-sized mines. Specifically, by constructing footwall transport roadways and mining risers within the stable surrounding rock of the ore body, and excavating rock-cutting veins that penetrate the ore body in layers, an inherently safe working space completely isolated from the collapse zone is provided for personnel. On this basis, shallow-hole ore extraction is adopted to minimize blasting vibration, and triangular pillars are reserved at the bottom of the stope to ensure smooth ore sluice passage. At the same time, by partially extracting ore after each layer of blasting and leaving ore as a buffer layer, the influx of loose ore-rock mixtures on both sides is suppressed in real time. Thus, under conditions that do not rely on backfilling, safe, efficient, and low-dilution recovery of intermediate pillar resources is achieved in an extremely unstable environment.

[0034] This invention provides a method for safe pillar recovery mining under stope collapse conditions. The stope follows the stope layout, perpendicular to the ore body strike. The pillars are 6-8m wide, with some pillars around 10m wide. The stope length is approximately 11m, equal to the ore body thickness on average, and the recovery height is approximately 25m. Previously, due to the use of open-stope mining and inadequate backfilling, the stope became filled with a mixture of ore and rock, making pillar recovery difficult, especially for small and medium-sized mines. To reduce the cut-to-cut ratio, a combination of external risers and drilling through the vein is used to recover ore safely and efficiently while minimizing the cut-to-cut ratio. The specific recovery method is as follows: First, a footwall haulage roadway is excavated along the vein 5-6 meters from the ore body boundary in the footwall. A mining raise is then drilled at the corresponding position of the pillar in the footwall haulage roadway, connecting to the upper and middle sections to form a safety passage. A drilling vein is placed every 5-6 meters within the mining raise, extending all the way to the footwall ore body boundary. Since the sides of the pillar stope are composed of collapsed loose material, to prevent the loose ore and rock from the original stope from mixing into the pillar stope during mining, the stratification height of the pillar stope is reduced. Inclined upward blast holes are constructed within the drilling vein, and blasting is gradually carried out to the footwall ore and rock boundary using a retreating method. A triangular pillar is reserved within the bottommost drilling vein to ensure that the ore mined later falls to the bottom of the stope, facilitating ore extraction at the bottom. Only a portion of the ore from the bottom is mined initially; the remaining portion serves as the ore drop space for the next stratum and prevents the collapse of the original ore and rock mixture into the stope. Drill blast holes in the upper layer of rock-cutting veins, and after the blasting of the upper layer is completed, ore is extracted at the bottom until all ore in the pillar stope is mined.

[0035] The main preparatory and cutting works include the lower footwall transport roadway, mining raise, rock drilling vein, and vein roadway. The mining raise is located 5-6 meters away from the ore body boundary. Blasting holes are drilled in the rock drilling vein, extending all the way to the stope boundary. Retreating blasting is used. For the first layer, a triangular pillar is reserved in the upper footwall within the rock drilling vein. Only a portion of the ore falling after the first layer is blasted is extracted. For the second layer, workers enter the rock drilling vein through the lower footwall mining raise to continue retreating mining. Ore extraction only needs to be done at the bottom. This process is repeated within the rock drilling vein until the entire pillar stope is mined out.

[0036] Example 1 Please refer to Figures 1 to 3 As shown, Embodiment 1 of the present invention provides a safe recovery mining method for pillars under conditions of stope collapse. In order to ensure the safety of mining personnel, all drilling and channeling of each layer is carried out in the mining raise. The layer height is 5-6m. The drilling and channeling extends from the footwall of the ore body through the ore body to the boundary of the hanging wall ore body. During mining, personnel use shallow holes to cut ore in the drilling and channeling to prevent the blasting vibration from having a large impact, which would cause the loose ore-rock mixture on both sides to collapse into the pillar stope during blasting, resulting in dilution loss.

[0037] The specific implementation steps are as follows: S0, Mining Area Layout The stope adopts the original stope layout, perpendicular to the ore body strike. The width of the pillars is 6-8m, with some areas exceeding 10m. The stope length is consistent with the ore body thickness, averaging approximately 11m. The vein roadway 4 follows the original development engineering, with a stage height of approximately 30-40m. This invention only targets the recovery of pillars, eliminating the need for backfilling of collapsed stopes. By optimizing the preparatory engineering layout and mining process, the safe recovery of pillar resources is achieved.

[0038] S1, Preparation and Cutting Engineering Layout The main preparatory and cutting works include the lower transport roadway 1, the mining raise 2, and the cross-vein roadway 5. The specific construction steps are as follows: First, along the footwall of the ore body, at a distance of 5-6m from the ore body boundary, a footwall transport roadway 1 is excavated along the strike of the ore body, serving as the core passage for ore transportation and equipment passage; at the same time, the vein roadway 4 developed in the early stage of the mine is reused, which is constructed directly in the footwall of the ore body to reduce the cost of additional tunneling work.

[0039] At the position of the pillar corresponding to the lower transport roadway 1, the mining raise 2 is excavated vertically upward. The top of the mining raise 2 connects to the upper and middle section along the vein roadway 10 and the through vein roadway 5, forming a safe passage for personnel passage and ventilation. Its cross-sectional dimensions are adapted to the needs of personnel and equipment entry and exit.

[0040] At the bottom of the mining area, the cross-vein roadway 5 was excavated, which runs from the footwall through the ore body to the boundary of the hanging wall.

[0041] S2, Layered operation channel formation Within the mining riser 2, drilling veins 3 are excavated in layers at vertical intervals of 5-6 meters. Each drilling vein 3 passes through the ore body from the footwall to the upper boundary of the ore body. The roadway cross-section is 3×3m, meeting the needs of personnel operations and drilling equipment operation. This reduces the mining height and prevents the premature mixing of ore-rock mixture 11 from the collapse of the mining areas on both sides into the pillar mining area.

[0042] In the bottommost cross-cutting roadway 5, a triangular pillar 9 is reserved near the upper part of the cross-cutting roadway 4. The purpose of the triangular pillar 9 is to ensure that the ore mined from the upper layers can fall back to the bottom of the stope along its natural flow path, facilitating subsequent shoveling and unloading. Alternatively, the ore in the area of ​​the triangular pillar 9 can be mined first, and then the area can be filled with high-strength backfill material to minimize ore loss. Due to the long stope length, the triangular pillar 9 is reserved to solve the problem of bottom ore extraction in order to ensure that the ore mined from the upper layers can fall back to the bottom.

[0043] Ventilation system layout: This invention constructs a complete ventilation loop through the mining raise 2 to ensure air circulation at the working face. Fresh air flows from the bottom of the stope through the lower transport roadway 1 into the mining raise 2, and then through each layer of drilling veins 3 to reach the mining face; polluted air generated during operation flows back to the mining raise 2 through the drilling veins 3, and then flows into the upper and middle section passages to be discharged to the surface, forming a stable ventilation cycle and ensuring the safety of personnel during operation.

[0044] S3, Layered mining operation The mining process employs a bottom-up, layered, retreating shallow-hole ore extraction technique, with the specific steps as follows: After the bottom layered cross-cutting roadway 5 is formed, the ore volume is deducted from the reserved triangular pillars 9. Workers enter the cross-cutting roadway 5 from the mining raise 2 and perform stripping operations using shallow holes until the boundary of the pillar stope is reached. During stripping, special attention must be paid to the collapsed ore-rock mixture 11 within the original stope to prevent it from prematurely mixing into the pillar stope. A retreat mining method is adopted. Based on the fact that both sides of the pillars are collapsed loose material, rock drilling through the cross-cutting roadway 3 is used to ensure the safety of personnel during mining operations within the stope.

[0045] After stripping and blasting, a loader is used to partially extract ore in the vein roadway 5 and the adjacent vein roadway 4, releasing only a portion of the ore, while the remaining ore is temporarily left in the stope. The temporarily left ore serves two purposes: firstly, as a stepping stone for the working platform of the next layer of mining, and secondly, as a barrier to prevent the collapse of the original stope's ore-rock mixture 11 into the pillar stope.

[0046] During the previous layer mining, the workers entered the corresponding layer height of the rock drilling vein 3 through the mining raise 2. At the very end of the rock drilling vein 3, near the hanging wall, they constructed inclined blast holes 7. The blast holes 7 were shallow holes. Using shallow holes to cut ore can effectively avoid the impact of medium-deep blasting on the original stope, which would make it difficult to control the loss of ore dilution. After blasting, it may affect the rock-rock mixture 11 that collapsed in the stope.

[0047] After the blast hole 7 is completed, a retreating blasting method is used to gradually blast to the boundary of the footwall ore. The blasted ore, guided by the triangular pillar 9, naturally slides to the bottom of the stope. After the blasting of this layer is completed, local ore extraction is carried out through the bottom passage, and some ore is repeatedly reserved as the working platform for the next layer and as a barrier against collapse.

[0048] The operation is carried out layer by layer upwards in accordance with the above steps. The workers always operate within the rock drilling vein 3 to avoid direct exposure to the environment of the collapsed rock-ore mixture 11 in the stope, until the entire pillar stope is mined out, and finally the ore is extracted in a concentrated manner.

[0049] S4, Mining Management After all the layered mining is completed, the ore is extracted through the lower haulage roadway. The reserved guide pillars are used to guide the ore to the bottom of the stope for easy loading and unloading operations.

[0050] In summary, this invention provides a method for the safe recovery of pillars under conditions of stope collapse, relating to the field of underground mining technology. Addressing the challenge of pillar recovery in stopes filled with ore-rock mixtures due to untimely backfilling during open-stope mining, the method involves arranging the stope perpendicular to the ore body strike. This is achieved by excavating a lower footing transport roadway and a mining raise within the footing of the ore body, and installing drilling veins at 5-6m intervals connecting the upper and lower footings within the mining raise. Triangular pillars are pre-reserved at the bottom. A bottom-up, layered, shallow-hole, retreating blasting process is employed, temporarily retaining some ore as a working platform and a barrier against collapse. Personnel always operate within the drilling veins, achieving safe pillar recovery without the need for backfilling. This method is suitable for small and medium-sized mines, significantly reducing the mining-to-cut ratio, effectively controlling ore dilution, and significantly improving resource recovery rate, achieving economical, efficient, and safe recovery of pillars in collapsed stopes.

[0051] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for safe recovery mining of ore through shallow-hole pillars under conditions of stope collapse, characterized in that, For ore bodies with collapsed and unfilled stopes and pillars flanked by a mixture of collapsed ore and rock, the existing stope layout is adopted, perpendicular to the ore body strike. Only the pillar ore is recovered, without stope backfilling. The specific steps include: S1, Preparatory work layout: A footwall transport roadway parallel to the strike of the ore body is excavated in the footwall surrounding rock; and a mining riser is excavated at the corresponding pillar position in the footwall transport roadway; the mining riser is connected to the upper and middle sections to form a safety passage; S2, Formation of Layered Operation Channel: In the mining riser, rock drilling veins are excavated in layers along the vertical direction, the rock drilling veins extending from the lower boundary of the ore body to the upper boundary of the ore body; ore guide pillars are reserved in the bottommost rock drilling vein; S3, Layered mining operation: Personnel enter the mining shaft from the lower transport roadway, and then enter the drilling veins of each layer. Under the protection of the drilling veins, retreat mining is carried out, using shallow hole ore cutting method, and the pillar ore body is mined from bottom to top. S4, Ore Management: After all the layered mining is completed, the ore is extracted in a centralized manner through the lower transport roadway. The reserved guide pillars are used to guide the ore to the bottom of the stope for easy loading and unloading operations.

2. The method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions according to claim 1, characterized in that, In step S3, the process of retreat mining is as follows: S31, starting from the bottom of the rock-drilled vein layer, personnel enter the rock-drilled vein and use the rock-drilled vein as the working space to construct blast holes, and adopt the shallow hole ore-dropping method for retreat blasting. S32, after blasting, some ore is released, and the remaining ore is temporarily left as a working platform for the next layer of mining and a barrier to prevent the mixed ore and rock from entering the collapsed ore-rock mixture. S33. Repeat steps S31 to S32 layer by layer from bottom to top until all the intercolumns are recovered.

3. The method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions according to claim 1, characterized in that, To prevent loose ore and rock from the original stope from mixing into the pillar stope during pillar mining, measures are taken to reduce the stratification height of the pillar stope; the stratification height of the rock drilling vein is 5-6 meters, and the roadway cross-section is 3 meters × 3 meters.

4. The method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions according to claim 1, characterized in that, In step S2, the ore guide pillar is a triangular pillar.

5. A method for safe recovery mining of ore from shallow-hole pillar-supported mines under conditions of stope collapse, as described in claim 2, is characterized in that... In step S31, the blast holes are arranged obliquely upwards, with a depth of 1.8~2.2m and a spacing of 0.6~0.8m. Micro-delay blasting technology is used to control the intensity of blasting vibration and avoid causing instability of the rock-rock mixture on both sides.

6. The method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions according to claim 2, characterized in that, In step S32, the amount of remaining ore temporarily retained is 30% to 40% of the total amount of blasted ore in the layered blasting.

7. The method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions according to claim 1, characterized in that, During the mining process, forced ventilation is used. Fresh air flows sequentially through the lower transport roadway, mining shaft, rock drilling vein, and working face; polluted air enters the mining shaft through the rock drilling vein and is discharged to the surface through the upper and middle section of the drilling vein, forming a ventilation loop.

8. A method for safe recovery mining of ore through shallow-hole pillars under conditions of stope collapse, as described in claim 2, is characterized in that... The width of the pillars is 6 to 10 meters, the length of the stope is the same as the thickness of the ore body, and the mining height is 25 to 60 meters.

9. A method for safe recovery mining of ore from shallow-hole pillar-supported mines under conditions of stope collapse, as described in claim 1, is characterized in that... The distance between the mining riser and the lower boundary of the ore body is 5 to 6 meters, and the cross-sectional dimensions of the lower transport roadway are adapted to the passage requirements of the loader.

10. A method for safe recovery mining of ore through shallow-hole pillars under stope collapse conditions, as described in claim 1, characterized in that, The method is applicable to ore bodies where the mine collapses and the interior is filled with a mixture of ore and rock after the mine was mined using the open-field method and not backfilled in time.

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